On 26.1.2022 14.49, Hongyu Xie wrote: >> Anyway, why is this unique to this one driver? Why does it not show up >> for any other driver? > The whole thing is not about a particular driver. The thing is xhci_urb_enqueue shouldn't change the return value of xhci_check_args from -ENODEV to -EINVAL. Many other drivers only check if the return value of xchi_check_args is <= 0. Agree, lets return -ENODEV when appropriate. >> >>> The whole point is, if xhci_check_args returns value A, xhci_urb_enqueque >>> shouldn't return any >>> other value, because that will change some driver's behavior(like r8152.c). >> But you are changing how the code currently works. Are you sure you >> want to have this "succeed" if this is on a root hub? > Yes, I'm changing how the code currently works but not on a root hub. >> >>> 2."So if 0 is returned, you will now return that here, is that ok? >>> That is a change in functionality. >>> But this can only ever be the case for a root hub, is that ok?" >>> >>> It's the same logic, but now xhci_urb_enqueue can return -ENODEV if xHC is >>> halted. >>> If it happens on a root hub, xhci_urb_enqueue won't be called. >>> >>> 3."Again, this means all is good? Why is this being called for a root hub?" >>> >>> It is the same logic with the old one, but now xhci_check_streams_endpoint >>> can return -ENODEV if xHC is halted. >> This still feels wrong to me, but I'll let the maintainer decide, as I >> don't understand why a root hub is special here. > > Thanks please. usb_submit_urb will call usb_hcd_submit_urb. And usb_hcd_submit_urb will call rh_urb_enqueue if it's on a root hub instead of calling hcd->driver->urb_enqueue(which is xhci_urb_enqueue in this case). xhci_urb_enqueue() shouldn't be called for roothub urbs, but if it is then we should continue to return -EINVAL xhci_check_args() should be rewritten later, but first we want a targeted fix that can go to stable. Your original patch would be ok after following modification: if (ret <= 0) return ret ? ret : -EINVAL; Thanks -Mathias
